The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
John A Hoskins - One of the best experts on this subject based on the ideXlab platform.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 4 mechanistic considerations regarding the failure to observe Anthophyllite asbestos mesotheliomas in humans
Environment and Pollution, 2018Co-Authors: Edward B Ilgren, John A HoskinsAbstract:Anthophyllite is an amphibole mineral formed through a prograde metamorphism of magnesium-rich ultramafic talcose rocks through increasing pressure and temperature and dehydration. The talc and Anthophyllite are in phase equilibrium. Anthophyllite asbestos is therefore not a ‘contaminant’ of talc but a product derived from it. Fibrous talc, or so-called transitional fibers, are Anthophyllite fibers undergoing retrograde degeneration. In its fibrous asbestiform state, Anthophyllite differs in several fundamental ways from other commercially exploited forms of amphibole asbestos of which there are two broad families: monoclinic and orthorhombic. The more common forms of commercial amphibole asbestos such as crocidolite and amosite are monoclinic. The Anthophyllites are orthorhombic. The differences between the two crystal systems are reflected at the level of the basic amphibole-structure in a greater overall fiber width dimensional profile and a significant reduction in microstructural strength. Strength reduction most probably arises at the cellular level and is particularly pronounced within the thinner population of fibers. Here microstructural differences, due in significant part to stacking defects in the basic amphibole structure, can account for these observations. The lack of an observed attendant mesothelioma risk following exposure to Anthophyllite and transitional fibers in humans is a consequencel of these microstructural features that appear to differentiate them from the equidimensional monoclinic forms of amphibole asbestos such as South African crocidolite and amosite.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 3 studies of american and japanese Anthophyllite asbestos additional supportive evidence
Environment and Pollution, 2018Co-Authors: Edward B Ilgren, John A HoskinsAbstract:The largest anthopyllite deposits in the world are found in Finland and it is from here that most of the commercial Anthophyllite derives. However, other large deposits exist in both North America and Japan. Commercial production has existed in both these countries although not on a scale which matches the Finnish mines. Small deposits are known from several other countries but, apart from minor exploitation in India no significant mining has taken place. The North American deposits are primarily in the Eastern US states, mostly Maryland, Georgia and North Carolina although there was also extensive exploration in Alabama. In Japan, the major mining site was at Matsubase on the southermost island of Kyushu. Although these mines and attendant commercial concerns operated for decades and under conditions of high dust exposure no mesothelioma clusters are known from the mining areas.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 2 further epidemiological studies of occupational domestic and environmental exposure to finnish Anthophyllite asbestos
Environment and Pollution, 2018Co-Authors: Edward B Ilgren, John A HoskinsAbstract:Although people in all sectors of the Finnish Anthophyllite industry, including their families, have been heavily exposed to Anthophyllite there is no evidence for even a single proven case of attributable mesothelioma. A few cases have been claimed but the evidence either, that they were mesotheliomas or that amphibole exposure was solely to Anthophyllite is, in every case examined, insufficient. Even among the population who lived in Karelia in Central Finland who were exposed domestically or enviromentally to Anthophyllite released during agricultural and various domestic activities and during transport from the mines, Finnish epidemiology found no risk of mesothelioma. There is also an absence of mesotheliomas reported in the earlier Finnish literature. This anomaly compared to the effects of exposure to other amphiboles is strong support for the role of fiber width in mesothelioma production. Anthophyllite, though, is not without clinical effect. As screening techniques improved it was discovered that of every person over the age of 65 years, one third living in Karelia had bilateral pleural plaques. The area was henceforth called the Endemic Pleural Plaque (EPP) zone. Radiographic analysis of the residents living in the district of Kuusjarvi led to suggestions that the cases resulted from asbestos blown from the Paakila facility via fiber drift as far away as 30 km. Later studies showed that ‘fiber drift’ was very unlikely to be a factor in the radiological findings thus observed.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 1 epidemiological studies of finnish Anthophyllite asbestos
Environment and Pollution, 2017Co-Authors: Edward B Ilgren, John A HoskinsAbstract:Anthophyllite asbestos only occurs in a few parts of the world in sufficient quantities to be mined. The largest deposits of Anthophyllite asbestos occur in Finland where it was mined for more than 75 years and very extensively used and distributed, anciently, for more than six millennia. Anthophyllite is one of the five minerals known collectively as amphibole asbestos. Studies of the effect of these five mineral fibre types when inhaled have shown that fibre width is an important determinant of mesothelioma induction. Only the “thinner” fibres or those with fiber diameter dimensional profiles predominantly less than 0.25 – 0.30 µm, are clearly mesotheliogenic. The “thicker” ones or those whose predominant widths are greater than these diameters do not appear to show an observable attendant risk of mesothelioma. Observations based on studies of at least, two “thick” forms of amphibole asbestos support these hypotheses. The one is Bolivian crocidolite; the other Finnish Anthophyllite. The Finnish Anthophyllite industry presents an important opportunity to study the robustness of the theory that fibre width is key to mesothelioma genesis as vast numbers of people in all sectors of the Finnish industry and their families have historically incurred massive fiber exposures sufficient to cause a gross excess of asbestosis. Nonetheless, in spite of these long term, high dose exposures clear evidence for a mesothelioma risk due to Anthophyllite asbestos is still lacking.
Edward B Ilgren - One of the best experts on this subject based on the ideXlab platform.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 4 mechanistic considerations regarding the failure to observe Anthophyllite asbestos mesotheliomas in humans
Environment and Pollution, 2018Co-Authors: Edward B Ilgren, John A HoskinsAbstract:Anthophyllite is an amphibole mineral formed through a prograde metamorphism of magnesium-rich ultramafic talcose rocks through increasing pressure and temperature and dehydration. The talc and Anthophyllite are in phase equilibrium. Anthophyllite asbestos is therefore not a ‘contaminant’ of talc but a product derived from it. Fibrous talc, or so-called transitional fibers, are Anthophyllite fibers undergoing retrograde degeneration. In its fibrous asbestiform state, Anthophyllite differs in several fundamental ways from other commercially exploited forms of amphibole asbestos of which there are two broad families: monoclinic and orthorhombic. The more common forms of commercial amphibole asbestos such as crocidolite and amosite are monoclinic. The Anthophyllites are orthorhombic. The differences between the two crystal systems are reflected at the level of the basic amphibole-structure in a greater overall fiber width dimensional profile and a significant reduction in microstructural strength. Strength reduction most probably arises at the cellular level and is particularly pronounced within the thinner population of fibers. Here microstructural differences, due in significant part to stacking defects in the basic amphibole structure, can account for these observations. The lack of an observed attendant mesothelioma risk following exposure to Anthophyllite and transitional fibers in humans is a consequencel of these microstructural features that appear to differentiate them from the equidimensional monoclinic forms of amphibole asbestos such as South African crocidolite and amosite.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 3 studies of american and japanese Anthophyllite asbestos additional supportive evidence
Environment and Pollution, 2018Co-Authors: Edward B Ilgren, John A HoskinsAbstract:The largest anthopyllite deposits in the world are found in Finland and it is from here that most of the commercial Anthophyllite derives. However, other large deposits exist in both North America and Japan. Commercial production has existed in both these countries although not on a scale which matches the Finnish mines. Small deposits are known from several other countries but, apart from minor exploitation in India no significant mining has taken place. The North American deposits are primarily in the Eastern US states, mostly Maryland, Georgia and North Carolina although there was also extensive exploration in Alabama. In Japan, the major mining site was at Matsubase on the southermost island of Kyushu. Although these mines and attendant commercial concerns operated for decades and under conditions of high dust exposure no mesothelioma clusters are known from the mining areas.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 2 further epidemiological studies of occupational domestic and environmental exposure to finnish Anthophyllite asbestos
Environment and Pollution, 2018Co-Authors: Edward B Ilgren, John A HoskinsAbstract:Although people in all sectors of the Finnish Anthophyllite industry, including their families, have been heavily exposed to Anthophyllite there is no evidence for even a single proven case of attributable mesothelioma. A few cases have been claimed but the evidence either, that they were mesotheliomas or that amphibole exposure was solely to Anthophyllite is, in every case examined, insufficient. Even among the population who lived in Karelia in Central Finland who were exposed domestically or enviromentally to Anthophyllite released during agricultural and various domestic activities and during transport from the mines, Finnish epidemiology found no risk of mesothelioma. There is also an absence of mesotheliomas reported in the earlier Finnish literature. This anomaly compared to the effects of exposure to other amphiboles is strong support for the role of fiber width in mesothelioma production. Anthophyllite, though, is not without clinical effect. As screening techniques improved it was discovered that of every person over the age of 65 years, one third living in Karelia had bilateral pleural plaques. The area was henceforth called the Endemic Pleural Plaque (EPP) zone. Radiographic analysis of the residents living in the district of Kuusjarvi led to suggestions that the cases resulted from asbestos blown from the Paakila facility via fiber drift as far away as 30 km. Later studies showed that ‘fiber drift’ was very unlikely to be a factor in the radiological findings thus observed.
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Anthophyllite asbestos the role of fiber width in mesothelioma induction part 1 epidemiological studies of finnish Anthophyllite asbestos
Environment and Pollution, 2017Co-Authors: Edward B Ilgren, John A HoskinsAbstract:Anthophyllite asbestos only occurs in a few parts of the world in sufficient quantities to be mined. The largest deposits of Anthophyllite asbestos occur in Finland where it was mined for more than 75 years and very extensively used and distributed, anciently, for more than six millennia. Anthophyllite is one of the five minerals known collectively as amphibole asbestos. Studies of the effect of these five mineral fibre types when inhaled have shown that fibre width is an important determinant of mesothelioma induction. Only the “thinner” fibres or those with fiber diameter dimensional profiles predominantly less than 0.25 – 0.30 µm, are clearly mesotheliogenic. The “thicker” ones or those whose predominant widths are greater than these diameters do not appear to show an observable attendant risk of mesothelioma. Observations based on studies of at least, two “thick” forms of amphibole asbestos support these hypotheses. The one is Bolivian crocidolite; the other Finnish Anthophyllite. The Finnish Anthophyllite industry presents an important opportunity to study the robustness of the theory that fibre width is key to mesothelioma genesis as vast numbers of people in all sectors of the Finnish industry and their families have historically incurred massive fiber exposures sufficient to cause a gross excess of asbestosis. Nonetheless, in spite of these long term, high dose exposures clear evidence for a mesothelioma risk due to Anthophyllite asbestos is still lacking.
E B Ilgren - One of the best experts on this subject based on the ideXlab platform.
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reply to the readership regarding ilgren hoskins 2018 Anthophyllite mesothelioma articles
Environment and Pollution, 2019Co-Authors: E B IlgrenAbstract:Reply to the Readership regarding Ilgren & Hoskins (2018) Anthophyllite Mesothelioma Articles.
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Reply to the Readership regarding Ilgren & Hoskins (2018) Anthophyllite Mesothelioma Articles
Environment and Pollution, 2019Co-Authors: E B IlgrenAbstract:Reply to the Readership regarding Ilgren & Hoskins (2018) Anthophyllite Mesothelioma Articles.
Jill Murray - One of the best experts on this subject based on the ideXlab platform.
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malignant mesothelioma in a patient with Anthophyllite asbestos fibres in the lungs
Annals of Occupational Hygiene, 2010Co-Authors: James I Phillips, Jill MurrayAbstract:The amphibole asbestos, Anthophyllite, is associated with asbestos-related disease in humans, along with mesothelioma in animal models. In humans, however, there are only three cases of histologically proven malignant mesothelioma of the pleura associated with Anthophyllite that have been documented in the English-language literature. A fourth case is presented in a man who lived in South Africa and had Anthophyllite in his lung. Anthophyllite was never commercially mined in South Africa. Using scanning electron microscopy, his lung fibre burden was calculated to be 358 000 fibres and 31 000 asbestos bodies per gram of dry weight of lung tissue. The mean aspect ratio of the Anthophyllite fibres in the lung was 41.2 (SD 5 28.8). No other types of asbestos were detected in the lung. His exposure was almost certainly occupational. He worked in the plastic manufacturing industry and was exposed to talc and asbestos blankets that were used to insulate machinery.
Eiji Yano - One of the best experts on this subject based on the ideXlab platform.
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Reactive oxygen metabolite production induced by asbestos and glass fibers: effect of fiber milling.
Industrial Health, 2020Co-Authors: Toyoto Iwata, Eiji YanoAbstract:Particle stimulated chemiluminescence (CL) production by human polymorphonuclear leucocytes (PMN) has been utilized to evaluate the pathogenicity of mineral and glass fibers with the understanding that reactive oxygen metabolites (ROM) production as measured by CL is etiopathogenically related to fiber toxicity. In the present study to investigate the specific pathogenic role of fiber number and dimensions, CL production from PMN exposed to Anthophyllite asbestos mineral and glass fiber samples milled for different time periods was measured. Almost all the fibrous particles in the glass fiber sample were destroyed after milling for 30 minutes. With Anthophyllite, the total number of fibrous particles remained almost constant for up to 240 minutes of milling, although the size of fibrous particles was reduced. CL produced by the same mass of glass fiber was elevated after milling for 15 minutes, but then declined when the milling time was further increased. Similarly, with Anthophyllite, the production of CL was elevated at the first period of milling for 30 minutes, but then declined at the longer milling times. The level of CL produced was not correlated to the total number of fibrous particles, for both the glass fiber and the Anthophyllite samples. Likewise for the glass fiber and Anthophyllite samples, no specific range of fiber dimension was correlated to the peak hight CL production. These findings indicate that neither the total number, nor the specific range of fiber dimension solely determines CL production. As a consequence, it may be concluded that other physiochemical factors, such as the surface reactive characteristics of milled fibers, may be more closely related to CL production by PMN.
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chemiluminescent detection of induced reactive oxygen metabolite production of human polymorphonuclear leucocytes by Anthophyllite asbestos
Environmental Research, 2002Co-Authors: Toyoto Iwata, Norihiko Kohyama, Eiji YanoAbstract:Incidences of lung cancer and pleural plaque have been reported in relation to exposure to Anthophyllite asbestos. To investigate the pathogenic mechanisms of Anthophyllite, chemiluminescence (CL) detection of reactive oxygen metabolite (ROM) generation of human polymorphonuclear leucocytes (PMN) stimulated by Anthophyllite asbestos was determined and compared with that of other asbestos and mineral fiber samples. When Anthophyllite fiber sample was mixed with the luminol-primed PMN, high levels of CL which exhibited a specific time course characterized by two separate peaks were induced. The CL induced by Anthophyllite sample was greater than that induced by chrysotile, crocidolite, and amosite asbestos. We further investigated the two peaks of CL using specific inhibitors of signal transduction mechanisms. The two peaks of CL by Anthophyllite sample were different in sensitivity to cytochalasin B and genistein; the former relates to the cytoskeleton-dependent mechanism and the latter has been shown to inhibit tyrosine kinase, which resides in the pathway to cause PMN activation. The strong ROM reaction of PMN by Anthophyllite suggests that the surface characteristics of the fiber may participate in the pathogenic mechanisms of Anthophyllite asbestos.